A switched network is described for example in DE 100 58 524 A1. Subscribers of a switched network can be computers, programmable logic controllers or other devices which exchange data with other machines, especially process such data. By contrast with bus systems in which any subscriber can reach any other subscriber directly via the data bus, a switched network exclusively involves point-to-point connections, i.e. a subscriber can only reach all other subscribers of the switched data network indirectly by appropriate forwarding of the data to be transmitted by means of one or more data connections (coupling units).
In distributed automation systems specific data must arrive at specific times at the subscribers for whom it is intended and be processed by the recipients. This is referred to as real-time-critical data or data traffic since, it the data does not arrive at its intended location at the right time, this can lead to undesirable results for the subscriber. At the same time non-real-time-critical data is created and must be transferred in switched networks.
DE 100 58 524 A1 makes provision for mixed operation of real-time-critical and non-real-time-critical data communication by transmitting data between two subscribers in each case, especially a sender and a receiver, in at least one transmission cycle with a configurable duration, with each 2 transmission cycle being subdivided into at least one first area for transmission of real-time-critical data for real-time control and at least one second area for transmission of non-real-time-critical data.
EP 0 789 470 A2 discloses a gateway which can be used within the framework of telecommunications. This connects networks intended for voice transmission (telephone networks) to data networks (LAN, WAN, Internet). By means of this gateway there can be access from one of these networks to the other network respectively. A signal which includes both voice streams and also data streams can be split up by a gateway and optionally sent via the voice network, the data network or via both networks.